225 ILCS 710/9.02
For the purpose of ascertaining facts in connection with any inspection, inquiry, or examination, the inspector shall have full power to compel the attendance of witnesses by subpoena, to take depositions on the service of proper or usual notice to the mine owner or operator as required in the taking of depositions, to administer oaths, and to examine, cross-examine, and take such testimony as may be deemed necessary for the information of the inspector.
The refusal by any person to obey a subpoena issued by the inspector, or the wilful hindrance or obstruction by any person of the inspector in the performance of any of his duties under this Act, shall constitute a Class A misdemeanor and shall be punished as hereinafter provided.
Any witness appearing before the inspector in response to a subpoena so issued, who shall knowingly and wilfully testify falsely to any material matter, shall be deemed guilty of perjury and upon conviction as by law provided, shall be punished for perjury.
225 ILCS 710/9.02